1. Field of the Invention
The present invention relates to a system and a method for tire pressure monitoring sensor diagnosis via a vehicle antitheft and entry system.
2. Background Art
Conventional automotive industry remote keyless entry (RKE) approaches have been implemented to communicate with a vehicle through the use of a hand held transmitter. The hand held transmitter is commonly implemented in connection with a key fob. Currently available conventional RKE transmitters may be separate units (i.e., key fobs), or the RKE transmitter assembly may be part of an ignition keyhead, preferably along with a vehicle immobilization transponder. Such RKE key fobs and keyheads generally utilize an antenna to transmit radio frequency (RF) signals to a vehicle in order to lock or unlock vehicle doors, open or close a vehicle sliding door, unlock a vehicle trunk, activate internal and/or external vehicle lights, and/or activate a “panic” alarm. Remote access systems using such RKE fobs and keyheads typically employ on-off keying (OOK) or amplitude shift keying (ASK) modulation schemes for the RF signals.
Conventional approaches for wireless monitoring of vehicle tire parameters, particularly tire pressure have been implemented. An exemplary tire monitoring system is described and shown in U.S. Pat. Nos. 5,600,301 and 5,463,374, which also describes a vehicle remote access device. In such tire monitoring systems, RF transmitters mounted inside each tire, typically adjacent the inflation valve stem, transmit information concerning tire pressure to a receiver located on-board the vehicle. The information delivered by the RF signals from the transmitters is subsequently conveyed to a vehicle operator, typically in the form of a display. Like conventional vehicle remote access systems, such conventional tire monitoring systems also typically employ OOK or ASK modulation schemes for the RF signals. When such modulation schemes are used, however, there can be strong adverse effects on reception of the RF signal, because the amplitude of a signal transmitted from a rotating tire can vary significantly during the period of the transmission.
Conventional vehicle immobilization approaches, in order to deter vehicle theft, are also known in the automotive industry. U.S. Pat. No. 5,670,933 illustrates an example of such an immobilization system. Such vehicle anti-theft devices typically employ low frequency (LF) transponders in a vehicle ignition keyhead. In such systems, upon insertion of the vehicle ignition key into the vehicle ignition keyhole, an interrogation signal is sent (i.e., transmitted, broadcast, presented, etc.) by the vehicle. In response, the keyhead transponder transmits an encrypted code to a control unit, such as a microprocessor, on-board the vehicle. When the code sent by the transponder is valid (i.e., the control unit authenticates the received code), the control unit generates a signal operative to permit the vehicle to be activated. However, when the code is not received by the control unit, or when the code is not valid (i.e., the control unit cannot authenticate the received code), the control unit generates a signal operative to immobilize the vehicle, for example, by cutting off power to the fuel supply for the vehicle engine.
Conventional approaches for shared vehicle remote access, tire monitoring and vehicle immobilization are also known in the automotive industry. U.S. Pat. No. 6,420,967 illustrates an example of such an immobilization system. Such a system and method employs a combined RKE, tire monitoring and vehicle immobilization receiver and a single microprocessor controller. Such a system and method uses an OOK or ASK modulation scheme for RKE, while employing frequency shift keying (FSK) modulation scheme for tire monitoring. Still further, such a system and method provides an RF link for implementation in the vehicle immobilization.
A number of conventional vehicle TPM systems implement an existing RF interface (e.g., an RKE interface) to the TPM receiver. Increasingly, conventional vehicle TPM systems implement LF command signals. A number of conventional TPM sensors implement an LF command interface that is configured to provide sensor testing and diagnosis. The LF command interface is typically implemented such that the TPM sensor manufacturer and service personnel (e.g., vehicle dealership personnel, etc.) using specialized (sometimes vehicle specific) tools can perform the TPM sensor testing and diagnosis during manufacture, retrofit, replacement, etc. operations without the service personnel mounting the TPM sensor in a wheel assembly and mounting the wheel assembly on the respective vehicle prior to the testing and/or diagnosis. The TPM sensor testing and diagnosis can be performed without having to mount the TPM sensor in a wheel and mount the wheel on a vehicle via the specialized equipment that is available to the TPM sensor manufacturer and authorized service personnel such as vehicle dealership personnel.
However, when personnel other than dealership mechanics or manufacturer technicians have a need to determine if a TPM sensor is working properly, the TPM sensor typically must first be installed in the wheel assembly, the wheel assembly is balanced, then the wheel is installed on the vehicle. The vehicle TPM system is then operated in a test mode to determine TPM sensor operation. However, when the TPM sensor is not working properly (e.g., due damage from a flat tire, or the like), a significant amount of time and cost are expended prior to determination of proper TPM sensor operation. When the TPM sensor does not work properly and must be repaired or replaced, the time and cost are wasted.
Thus, there exists a need and an opportunity for a system and a method to quickly perform TPM sensor test and diagnosis before the TPM sensor is fastened to a wheel and the wheel is installed on a vehicle. Such a system and method may implement a new and innovative TPM sensor test and diagnosis, and result in the saving of a significant amount of time and cost when compared to conventional approaches to TPM sensor test and diagnosis.